As a result of the present experimental program, the upper limits of steady-state power dissipation at a stationary, solid target of a D-T neutron generator will be evaluated. The operating ranges for chemical stability of ScD2 and ErD2 targets will be determined for ion energies of 200 keV and power densities of 4 kW/cm2. Preliminary data indicate that ScD2 is chemically stable under ion beam bombardment at ion energies of 150 keV and power densities of greater than 3 kW/cm2. Full beam power tests will begin as soon as preliminary target cooling experiments are completed. Based on these data and on the successful design and operation of the deuterium ion accelerator that was built for the above experiments, it is now feasible to propose that a D-T neutron generator be designed, built, and evaluated for use in cancer therapy. The neutron generator will be designed to produce a minimum of 10 to the thirteenth power n/s over its operational life of at least 100 hours. For adequate neutron collimation, the area of the neutron source perpendicular to the axis of the neutron beam will be 10 cm2 or less. A neutron collimator with an isocentric mount will be designed with the aid of modern neutron transport codes and evaluated as an integral part of the above D-T neutron generator. Radiation outside the neutron beam will be shielded by the collimator to less than one percent of the neutron beam radiation. Automatic controls will be incorporated in the neutron generator for its safe operation by nontechnical personnel. The following proposal is for a four-year program to develop the D-T neutron generator system described above.